This application claims priority to Japanese Patent Application No. 2001-101748 filed on Mar. 30, 2001, the disclosure of which is incorporated by reference in its entirety.
1. Field of the Invention
The present invention relates to a stage apparatus for performing a predetermined work while positioning a workpiece, etc. in a two-dimensional plane in a machining apparatus or a metering device, and also relates to a method of using the stage apparatus.
2. Description of Related Art
In this kind of apparatus, as shown in FIG. 9, generally, a pair of parallel guide rails 201A and 201B extending in a Y-axis-direction within a two-dimensional plane are provided on a base 200 made of a rigid member such as a metal plate. A lower table 202 slidably supported by the guide rails 201A and 201B is connected to a straight drive apparatus (not shown) fixed to the base 200. Furthermore, on the lower table 202, a pair of parallel guide rails 203A and 203B extending in an X-axis-direction within a two-dimensional plane are provided. An upper table 204 slidably supported by these guide rails 203A and 203B is connected to a straight drive apparatus (not shown) fixed to the lower table 202. Thereby, a workpiece laid on the upper table 204 can be positioned in the X and the Y-axis-directions.
In the aforementioned conventional stage apparatus, two tables 202 and 204 driven individually is disposed one on the other on the base 200. Accordingly, too much load will be applied to the base 200 and/or the lower table 202, and it is hard to equalize the dynamic characteristics of the upper and lower table 204 and 202. Furthermore, since the table load transfer path from the upper table 204 to the base 200 is relatively long, flexure and/or deformation tends to occur in a guide member.
Especially, since each guide rail 201A, 201B, 203A and 203B has assembly accuracy limitations, it is difficult to obtain high-precision straight moving characteristics and/or rectangular guiding characteristics of the upper and lower tables. Therefore, the fluctuation of the lower table 202 causes a slight inclination of the upper table 204 toward a predetermined axial-direction as shown by the dot-dash line. In other words, since the origin of the coordinate system of the upper table 204 is slightly displaced, an error may be easily produced at the time of positioning a workpiece to a predetermined coordinate position because the axis which defines the coordinates of the upper table 204 is displaced in accordance with the movement of the lower table 202, i.e., the so-called Abbe error is produced.
The Abbe error will be explained with reference to FIG. 10.
The lower table 202 moves by a desired distance Y in a Ys-axis-direction while being guided by the guide rails 201A and 201B on the base 200. However, if the guide rails 201A and 201B do not have high-precision linearity, a minute rotation displacement will be generated as shown by the dot-dash line in FIG. 10. On the other hand, the upper table 204 is guided by both the guide rails 203A and 203B fixed to the lower table 202, and moves by only the desired distance X in the Xs-axis-direction. In this case, a minute rotation displacement will be also generated.
Accordingly, when the measuring probe is disposed on the origin 0, the measuring probe originally measures the position (xe2x88x92X, xe2x88x92Y) of the table coordinate system Os-Xs-Ys. However, if the aforementioned minute rotation is generated, the measuring probe measures the position shifted by xcex94X, xcex94Y from the position (xe2x88x92X, xe2x88x92Y). In the case where the axis of the coordinate system for measuring the amount of movement of the upper and lower tables 204 and 202 does not coincide with the position of the measuring probe, it is said xe2x80x9cthere is an Abbe error.xe2x80x9d
On the other hand, apart from the aforementioned stage apparatus, for example, the following conventional stage apparatus as shown in FIG. 11 is known. In the apparatus, only one table 301 is supported on a base 300 via a noncontacting bearing (not shown). The table 301 is movable in two axis directions by guide bars 302 and 303 crossing at right angles on the base 300. Furthermore, laser interferometers 306 and 307 are provided at the positions which coincide with absolute-coordinate axes, respectively. Furthermore, bar mirrors 304 and 305 crossing at right angles are disposed on the table 301, while an X-axis-direction linear motor 308a and a Y-axis-direction linear motor 308b are provided on the base 300. The laser interferometer 306 and 307 observe the coordinate system and the measured value is fed back to a laser control system, so that the positioning is performed by the motors 308a and 308b. 
However, in this sage apparatus, a pair of driving portions are required for each axis, the X-axis and the Y-axis, and therefore the structure becomes complicated. Furthermore, it is very expensive because of the noncontacting bearing, the laser interferometers 306 and 307, etc. Accordingly, such an apparatus cannot be introduced easily.
It is an object of the present invention to provide a stage apparatus in which deflection, deformation, etc. of a member is suppressed because of the comparatively simple structure and dynamic characteristics in both axis-directions, X-axis-direction and Y-axis-direction, are equalized.
It is another object of the present invention to provide a stage apparatus which can secure high positioning accuracy without being influenced by the so-called Abbe error.
It is still another object of the present invention to provide a method of using the aforementioned stage apparatus.
According to the first aspect of the present invention, a stage apparatus, comprises:
a table disposed above the base so as to oppose to the base;
an X-axis-direction table support mechanism portion disposed between the base and the table for supporting the table in a state that the table is capable of moving in an X-axis-direction within a two-dimensional plane;
a Y-axis-direction table support mechanism portion disposed between the base and the table for supporting the table in a state that the table is capable of moving in a Y-axis-direction within a two-dimensional plane;
an X-axis-direction linear guide portion formed on an upper surface of the base and extending in the X-axis-direction;
a Y-axis-direction linear guide portion formed on the upper surface of the base and extending in the Y-axis-direction;
an X-axis-direction movable member provided so as to move along the X-axis-direction linear guide portion and connected to the Y-axis-direction table support mechanism portion;
a Y-axis-direction movable member provided so as to move along the Y-axis-direction linear guide portion and connected to the X-axis-direction table support mechanism portion;
an X-axis-direction straight drive mechanism fixed to the base for driving the X-axis-direction movable member; and
a Y-axis-direction straight drive mechanism fixed to the base for driving the Y-axis-direction movable member,
wherein the X-axis-direction linear guide portion and the Y-axis-direction linear guide portion are arranged in a rectangular cross positional relation forming a roughly xe2x80x9c+xe2x80x9d shape.
In this stage apparatus, by driving the X-axis-direction movable member with the X-axis-direction straight drive mechanism, this X-axis-direction movable member is displaced in the X-axis-direction along the X-axis-direction linear guide portion on the upper surface of the base. Thereby, the table moves in the X-axis-direction via the Y-axis-direction table support mechanism portion connected to and supported by the movable member. On the other hand, by driving the Y-axis-direction movable member with the Y-axis-direction straight drive mechanism, this Y-axis-direction movable member moves in the Y-axis-direction along the Y-axis-direction linear guide portion. The table moves to the Y-axis-direction via the X-axis-direction table support mechanism portion connected to and supported by the movable member.
In this case, since the table is supported by the movable member at the base side via the table support mechanism portion, the table load transfer path to the base is comparatively short. Thus, deflection or deformation can be suppressed. Furthermore, since one table is driven by each of the X-axis-direction straight drive mechanism and Y-axis-direction straight drive mechanism, the dynamic characteristics of both the drive systems coincide with each other. As a result, a stable movement of the table can be attained. Furthermore, a laser interferometer, etc. becomes unnecessary.
Since the X-axis-direction linear guide portion and the Y-axis-direction linear guide portion on the base are arranged in a rectangular cross relation forming a roughly xe2x80x9c+xe2x80x9d shape, even if the table slightly rotates in the moving direction due to the scattering of straight-line guide accuracy or rectangular accuracy, the center of rotation will be positioned on the normal line which passes the crossing point of the X-axis-direction linear guide portion and the Y-axis-direction linear guide portion. Accordingly, even if the table moves to a certain position, the central position of the minute rotation remains on the same coordinate position. Accordingly, the so-called Abbe principle will be met, which in turn can minimize the position error of the workpiece due to the minute rotation.
According to the second aspect of the present invention, a method of using a stage apparatus, the method comprises the steps of:
preparing a stage apparatus,
wherein the stage apparatus includes:
a table disposed above the base so as to oppose to the base;
an X-axis-direction table support mechanism portion disposed between the base and the table for supporting the table in a state that the table is capable of moving in an X-axis-direction within a two-dimensional plane;
a Y-axis-direction table support mechanism portion disposed between the base and the table for supporting the table in a state that the table is capable of moving in a Y-axis-direction within a two-dimensional plane;
an X-axis-direction linear guide portion formed on an upper surface of the base and extending in the X-axis-direction;
a Y-axis-direction linear guide portion formed on the upper surface of the base and extending in the Y-axis-direction;
an X-axis-direction movable member provided so as to move along the X-axis-direction linear guide portion and connected to the Y-axis-direction table support mechanism portion;
a Y-axis-direction movable member provided so as to move along the Y-axis-direction linear guide portion and connected to the X-axis-direction table support mechanism portion;
an X-axis-direction straight drive mechanism fixed to the base for driving the X-axis-direction movable member; and
a Y-axis-direction straight drive mechanism fixed to the base for driving the Y-axis-direction movable member,
wherein the X-axis-direction linear guide portion and the Y-axis-direction linear guide portion are arranged in a rectangular cross positional relation forming a roughly xe2x80x9c+xe2x80x9d shape; and
performing a predetermined work to the workpiece by setting the acting point on the workpiece so that a normal line from an acting point of the workpiece toward the upper surface of the base passes an intersection of the X-axis-direction linear guide portion and the Y-axis-direction linear guide portion on the upper surface of the base.
In this method of application, a predetermined measurement or processing can be performed correctly with no Abbe error even if minute rotation of the table occurs.
Other objects and the features will be apparent from the following detailed description of the present invention with reference to the attached drawings.